Element Composition of Tea Leaves and Tea Infusions and Its Impact on Health

Abstract

Tea infusion is the most frequently consumed beverage worldwide next to water, with about 20 billion cups consumed daily. In Taiwan, daily consumption averages 2.5 cups of tea infusion per person. Many studies have concluded that tea has numerous beneficial effects on health. However, some undesirable trace elements, such as arsenic, chromium, cadmium, lead, etc., are a concern. This study has three aims: (1) to measure the concentrations of arsenic and heavy metal elements, such as chromium, cadmium, and lead, as well as the essential trace elements contained in dried tea leaves of the common brands in Taiwan; (2) to determine the percentage released and concentration of each of these elements after infusion of these tea leaves with boiling water; (3) to assess the carcinogenic risk from daily tea consumption, to provide reference values for the general public. This study showed the total content of arsenic and heavy metals in green tea, oolong tea, and black tea produced in Taiwan was 0.11, 5.61, and 10.11 microg/g, respectively, indicating that the level of arsenic and heavy metal contamination of tea leaves was lower in Taiwan than other regions of the world. The hazard index (HI) of daily tea drinking of green tea, oolong tea, and black tea was low and within the bounds of safety (<1). Tea is an indispensable part of everyday life for many people in Taiwan, studies should continue to ensure that public health is maintained.

Simple and Fast Sample Preparation Procedure Prior to Multi-element Analysis of Slim Teas by ICP OES

“…Generally, the determination of total concentrations of various macro-and micro-elements in different teas as well as medicinal plants is carried out with the use of flame atomic absorption spectrometry (FAAS) (Aksuner et al 2012;Colak et al 2005;Kumar et al 2005;Li et al 2006;Malik et al 2008;Narin et al 2004a,b;Seenivasan et al 2008;Soylak et al 2007), graphite furnace atomic absorption spectrometry (GF AAS) (Dash et al 2008;Seenivasan et al 2008), inductively coupled plasma optical emission spectrometry (ICP OES) (Chen et al 2009;Dash et al 2008;Kara 2009;Malik et al 2008;Matsuura et al 2001;McKenzie et al 2010;Mierzwa et al 1998;Özcan et al 2008), inductively coupled plasma mass spectrometry (ICP MS) (Kara 2009;Matsuura et al 2001;Nookabkaew et al 2006;Shen and Chen 2008) and X-ray fluorescence spectrometry (XRFS) (Salvador et al 2002;Xie et al 1998). As a rule, the decomposition of the matrix of tea samples is an indispensable and mandatory step before their elemental analysis by the majority of these spectrometric methods.…”

“…As a rule, the decomposition of the matrix of tea samples is an indispensable and mandatory step before their elemental analysis by the majority of these spectrometric methods. Typically, the digestion is carried out by a conventional hot-plate or microwave-assisted heating of tea samples with oxidizing reagents, including HNO 3 , HNO 3 + H 2 O 2 , HNO 3 +H 2 SO 4 +H 2 O 2, HNO 3 +H 2 O 2 +HF, HNO 3 + HClO 4 , HNO 3 + HCl, HNO 3 + HCl + HF, (Aksuner et al 2012;Colak et al 2005;Kumar et al 2005;Narin et al 2004a,b;Dash et al 2008;Matsuura et al 2001;McKenzie et al 2010;Mierzwa et al 1998;Nookabkaew et al 2006;Salahinejad and Aflaki 2010;Shen and Chen 2008;Soylak et al 2007). Except for the mentioned wet ashing procedures, dry-ashing procedures, as described by the Association of Analytical Chemistry (Seenivasan et al 2008) or modifications of this official method (Chen et al 2009;Li et al 2006;Malik et al 2008;Narin et al 2004b), are also used at the stage of the sample preparation of tea before its spectrochemical analysis.…”

Oxalate, magnesium and calcium content in selected kinds of tea: impact on human health

“…Most of the elements in tea leaves are complexed by flavonols, catechols, tannins and polyphenols [11]. With respect to this, better leaching of some essential macroelements and trace elements from leaves into infusions was reported for green teas rather than black and oolong teas [1,33,37,41]. The variation in Ca extraction from the analyzed teas can be explained by the differences in plant's age at harvest or tea-growing conditions.…”

“…Tea is one of the most consumed beverages all over the world [1]. There are two species of Camellia sinensis: var.…”

Comparison and Validation of Different Alternative Sample Preparation Procedures of Tea Infusions Prior to Their Multi-Element Analysis by FAAS and ICP OES

“…In case of FAAS, it is particularly convenient in reference to selected metals that are highly abounded in tea infusions, i.e., Ca, Fe, K, Mg, Mn, and Na (Szymczycha-Madeja et al 2012). In addition, graphite furnace atomic absorption spectrometry (GFAAS) (JeszkaSkowron et al 2015;Wrobel et al 2000) and inductively coupled plasma mass spectrometry (ICP MS) (Milani et al 2015;Schwalfenberg et al 2013;Shen and Chen 2008;Sofuoglu and Kavcar 2008) were used. Among different sample preparation procedures reported so far for infusions of black (BTs) and green (GTs) teas before their spectrochemical analysis, it appears that no treatment and direct measurements of metals in them was preferred in case of FAAS (Dambiec et al 2013;Malik et al 2008;Memic et al 2014;Polechonska et al 2015), ICP OES (Altintig et al 2014;Derun 2014;Diniz et al 2015;Froes et al 2014;Malik et al 2008;Mehra and Baker 2007;Ozcan et al 2008;Ozdemir et al 2014;Street et al 2006, andGFAAS (Jeszka-Skowron et al 2015).…”